The following is a tabulation of some prior art that presently appears relevant:
U.S. patent DocumentsPat. No.Kind CodeIssue DatePatentee6,988,331B2Jan. 24, 2006Larry Holmberg8,087,117B2Jan. 3, 2012Irobot Corporation8,516,651B2Aug. 27, 2013Irobot Corporation7,801,645B2Sep. 21, 2010Sharper ImageAcquisition Llc7,057,501B1Jun. 6, 2006Darryl Davis6,400,311B1Jun. 4, 2002Honeywell International Inc.
U.S. patent application PublicationsPublication NrKind CodePubl. DateApplicant20040204792A1Oct. 14, 2004Taylor Charles E.,Parker Andrew J., et al.20040130685A1Jul. 8, 2004Lite-On technologyCorporation
Mobile automated devices are becoming increasingly common in consumer homes. These may include robotic vacuums, robotic mops, and other devices that move through environments autonomously. One problem that such devices face is effectively identifying dangerous drop-offs. Mobile automated devices are often unable to traverse stairs or ledges without damage, thus these and similar structures must be avoided. A need exists for a precise method to identify dangerous drop-offs and edges. A need exists for a method to differentiate between large edges that are dangerous and smaller elevation changes that are traversable.